import datetime

def create_time():
    """
    @return :返回当时时间
    """
    return datetime.datetime.utcnow()

def create_time_nmin_before(n=5):
    """
    @default n: = 5
    @return :返回n分钟前的时间
    """
    if not isinstance(n,(int,float)):
        n = 5
    return datetime.datetime.utcnow()-datetime.timedelta(minutes=n)